1. Field of the Invention
The present invention relates to a shaft structure to be installed in shafts used for various industrial machines, and a male component and a female component included in the shaft structure.
2. Description of the Background Art
Conventionally, there have been publicly well-known telescopic shafts each including male and female spline shafts to be incorporated into vehicle steering shafts (see FIG. 2 in Patent Document 1). Such a telescopic shaft has splines formed on an outer surface of the male spline shaft and an inner surface of the female spline shaft. Furthermore, an approximately 0.25 mm thick synthetic resin (nylon or the like) coating is formed on either of the outer surface of the male spline shaft or the inner surface of the female spline shaft.